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Message-ID: <CAP-5=fX296_EROp6D+zX4OOABOkwkHrE-2v7F0K=Jo5zSZ_-zw@mail.gmail.com>
Date: Fri, 29 Mar 2024 09:32:45 -0700
From: Ian Rogers <irogers@...gle.com>
To: Namhyung Kim <namhyung@...nel.org>, Changbin Du <changbin.du@...wei.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>, Kan Liang <kan.liang@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>, Adrian Hunter <adrian.hunter@...el.com>,
Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...nel.org>,
LKML <linux-kernel@...r.kernel.org>, linux-perf-users@...r.kernel.org
Subject: Re: [PATCH 0/4] perf annotate: Use libcapstone as a disasssembler
On Thu, Mar 28, 2024 at 4:20 PM Namhyung Kim <namhyung@...nel.org> wrote:
>
> Hello,
>
> As we've added libcapstone support, it's natural to use it for perf annotate
> as well. This change added the capstone support on x86 first. Other archs
> can be added later (by someone who can verify it doesn't break things).
>
> For now it tries to use capstone (if available) before objdump. But it
> doesn't support source file and line number info. So users should use the
> objdump (by passing --objdump=PATH option) if they need them. For example,
> this command line will keep the existing behavior (i.e. using objdump).
>
> # not to use capstone for disassembly
> $ perf annotate --objdump=objdump
>
> The capstone uses LLVM objdump style output which is slightly different than
> the GNU objdump. But it should not have differences besides that. I've
> verified the result of data type profiling and it produced the same output
> but gave me ~3x speedups.
>
> Thanks,
> Namhyung
I wanted to see what -fsanitize=address would think of libcaptstone
and no issues, so:
Tested-by: Ian Rogers <irogers@...gle.com>
Some thoughts:
- it may be worth adding to the commit message in "perf annotate:
Split out util/disasm.c" that there's no functional change,
- we lack perf annotate testing,
- it seems capstone should be opt-out rather than opt-in as a library
dependency (given the performance delta and the objdump interactions
are at best messy),
- if libcapstone could solve our addr2line issues too this would be great :-).
Thanks,
Ian
> Cc: Changbin Du <changbin.du@...wei.com>
>
>
> Namhyung Kim (4):
> perf annotate: Use ins__is_xxx() if possible
> perf annotate: Add and use ins__is_nop()
> perf annotate: Split out util/disasm.c
> perf annotate: Use libcapstone to disassemble
>
> tools/perf/util/Build | 1 +
> tools/perf/util/annotate.c | 1711 ++---------------------------------
> tools/perf/util/annotate.h | 59 +-
> tools/perf/util/disasm.c | 1739 ++++++++++++++++++++++++++++++++++++
> tools/perf/util/disasm.h | 112 +++
> 5 files changed, 1914 insertions(+), 1708 deletions(-)
> create mode 100644 tools/perf/util/disasm.c
> create mode 100644 tools/perf/util/disasm.h
>
> --
> 2.44.0.478.gd926399ef9-goog
>
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